Centrifugal pump



Feb. 20, 1934. p, A, BANCEL 1,948,157

CENTRIFUGAL PUMP Filed sept. 26, 1928 JNVENroR. Pa LZLBaIu'eL HLS ATTORNEY Patented Feb. 20, 1934 UNITED STATES CENTRIFUGAL PUMP Paul A.. Bancel, Montclair, N..J., assgnor to Ingersoll-Rand Company, Jersey City, N. J., a corporation of New Jersey Application September 26, 1928 Serial No. 308,492.

1 Claim.

'Ihis invention relates to centrifugal pumps and more particularly to improvements in pumps of the general type disclosed in the patent to James K. McIntyre No. 1,680,057 and filed Sepl tember 23, 1926, bearing Serial No. 137297.

The invention has for its object, to increase the eciency of a two stage centrifugal pump in which the suction pressure is extremely low, and toward this end the invention contemplates the interposition of means between the two stages of the pump so that a constant head may be maintained on the first stage impeller.

It has been found in actual practice that when a two stage pump, such as that disclosed in the above mentioned patent is in operation, at low loads the second stage wheel of the pump actually performs the entire work to be done while due to lack of water to be pumped, the first stage wheel of the pump is deprived of its load so that the same merely cavitates and churns the fluid with- 4 in the casing by virtue of the fact that there is an insuflicient head on the wheel. This is extremely disadvantageous if not a dangerous situation, for the wheel wears rapidly when at less than full head and the thrust of the second stage is no longer balanced, there being relatively little thrust developed by the rst stage impeller. This situation may be corrected in actual practice by placing an elevated loop between the discharge of the first stage and the inlet of the second stage of a two stage pump.

With these and many other objects in view, which will more readily appear as the nature of invention is better understood, the same consists in the construction, `combination and arrangement of parts to be more fully" descr-ibed, illustrated and claimed.

In the. accompanying sheet of drawing, the figure represents a hotwell pump as actually connected to the hotwell of a condenser and shows the loop interposed between the two stages of the pump.

The device involves in its general organization a main support 10, upon which there is a casing formed in two parts 11 and 12. The lower part 12, is provided with a base 13 and bearing support 14 for the drive shaft 15. Bearings 16 are-provided for the shaft and may be of any suitable description. The upper part 11 is adapted to be attached to the lower part 12 in any suitable manner, and the two parts 1 1 and 12 form stuffing boxes 17 which, with suitable packing .material 18 and glands 19, prevent the escape of liquid from the casing.

The pump is of the two stage type, there being 'secondstage impeller 21.

(Cl. 10S-109) provided a rst stage wheel 20 and a second stage or high pressure wheel 21, both stage wheels being supported and driven by the single central' shaft 15.

The rst stage wheel 20, is shown as being provided with a`relatively large inlet 22 in order that the velocity set up may be relatively low. Similarly, the outlets 23 from the rst stage wheel, are relatively large and the diameter of the wheel is comparatively small, in order that the periph- 05 eral, relative and absolute velocities may be kept low in this stage. The pump as shown is designed to bring the discharge pressure of the rst stage impeller up to at least atmospheric pressure.

Preferably the rst stage inlet 22 is connected to 7 a source of low pressure such as the condenser by means of a pipe 86. The details of the connection -are omitted to avoid unnecessary complication in the drawing. The second wheel or impeller 21, is provided with a comparatively small inlet .30 and a small discharge opening 31. This second impeller is designed to work with a slight pressure at its inlet.

The casing 12 of the pump is provided withv an inlet4 40 located between the two impellers 20 9 and 21. This inlet communicates with a passage 41 leading to the impeller inlet 22. The passage 41 is formed by webs 43 cast integrally with the upper and lower parts-11 and 12 of the casing. These webs also serve as a partition for part of the discharge passage leading to the shown between the web 43 and the lower portion of casing 12, and this partition serves topre vent the uid from passing from the discharge outlet 23 of the impeller 20 directly to the inlet 30 of the impeller 21, by causing the fluid to pass through an outlet 52 and through a loop 53 extending vertically, having a fall 54 communicating with an inlet 55 in the discharge passage to the second impeller inlet V30. In other words,` this loop is directly interposedbetween the two stages of the pump for a purpose to be more fully hereinafter set forth.

The second stage impeller a passage 60, leading to a discharge opening 61 for connection with a suitable delivery pipe (not shown).l The shaft 15 is provided with a suitable iiange 63 for connection with a source of power for rotating the impellers 20 and 21.

A partition 50 is 00 211s surrounded by l ,between the stages of the pump is that in the first stage the action is similar to a regular hotwell pump and thev first stage wheel lifts into what corresponds to a tank or fluid potential. The second stage pumps from the discharge of the loop and as the load on the pump is increased the higher the water rises in this side of the loop. At low loads the height of water on this side of the loop is not great and the excess work performed by the rst stage wheel is destroyed by free falling and vsplashing of the water over the top of the loop.

The device is shown as in actual operation as connected to hotwell H of the condenser C. These last elements are of the conventional type and no claim is made as to their novelty in this application. Their illustration in the accompanying drawing serves to illustrate the principlsof the invention. As clearly shown, a vacuum connection 85 leads from the top of the loop 53 to the outlet of the condenser C to equalize the vacuum in the loop and at the outlet to the condenser and to further aid the loop in performing its normal function of maintaining a full head on the first stage wheel. It will be clear to those skilled in the art that siphonic action in the loopmay be avoided by carrying the pipe 53 more than 32 feet above the outlet of the lower stage impeller.

I claim:

A multiple stage pumping system for evacuating a Variable pressure fluid supply including a two stage centrifugal pump adapted to be connected to the hotwell of a condenser and having a pair of impellers within a casing, each impeller operating to receive fluid from a fluid inlet and to discharge the same with increased head through a fluid outlet and means comprising a loop connecting the first stage fluid outlet and the second stage uid inlet and extending above the pump for maintaining constant fluid potential on the rst stage impeller, and means for maintaining substantial equal Vacuum pressure in the loop and at the outlet to the con- 

